Control system for refrigerating plant e.g. fridge or deep-freezer - has both compressor(s) and defroster connected to respective control circuits by one or more low voltage relays

摘要

The refrigerating plant has a cooling thermostat and a defrost clock, and is operated from the mains with electrical circuitry for at least one compressor and at least one defrosting heater with appropriate thermostat. For cooling, the compressor(s) is/are connected through one or more low voltage relays by a control circuit containing the cooling thermostat. For defrosting, the defrost clock is connected. The state of the defrost thermostat is checked electronically and the defrosting heater(s) activated through one or more further low voltage thermostats within a low voltage control circuit. An optic coupler is used to check the defrost thermostat's state. ADVANTAGE - Reduced material and construction costs with improved reliability.